This will probably go into the official code base. The problem with the relative symlinks is that LE uses a symlink itself to point from live to archive and the relative symlinks features resolves the final file, which is always the archive. The above workaround is needed to replace the path back to the symlink.

You can leve it on if it works now. Personally, I never needed the relative symlinks feature on a server, it had been implemented by someone who used a special network drive setup for /var/www, that's why it is off by default. But if you used it till now, then better keep it on.